The objective of this research proposal is to investigate the effect of sustained mechanical loading on nutrient transport and cell nutrition of the temporomandibular joint (TMJ) disc in order to better understand the biomechanical etiology of TMJ disorders and to develop a novel strategy for restoring tissue function. The TMJ disc serves to distribute stress, lubricate movement, and protect the articular surfaces of the joint. Millions of Americans are afflicted with TMJ disorders that can cause noticeable pain and limited functionality of the jaw. TMJ disc pathologies including disc derangement and degeneration are central to TMJ disorders, but are not well understood. It is generally believed that pathological mechanical loading, such as sustained compressive loading during jaw clenching and sudden traumatic impact, is the leading cause of TMJ disc derangement. Since the TMJ disc is a large avascular structure, transport of nutrients (e.g., oxygen and glucose) is primarily done through the passive transport mechanism of diffusion. Transport of nutrients and solutes through the extracellular matrix (ECM) is important in maintaining the normal function of tissues, so deviation from physiological levels can cause tissue necrosis and matrix degradation. Therefore, our general hypothesis is that sustained mechanical loading can alter solute transport and nutrient concentrations in the TMJ disc, resulting in changes to the cellular metabolism, tissue composition, and mechanical function, ultimately leading to disc pathologies. Aim 1: Examine the effect of mechanical strains on nutrient transport rates in the TMJ disc. Using custom designed diffusion chambers, passive oxygen and glucose transport can be measured through porcine tissue samples to quantify regional in vitro diffusive properties. The relationship between compressive strain and diffusivity will be developed to better understand TMJ disc nutrient transport pathways. Aim 2: Determine TMJ disc cell consumption rates for glucose and oxygen under various culture conditions. Glucose and oxygen consumption rates can be measured for TMJ disc cells by utilizing specialized probes and assays that are capable of determining solute concentrations at specific time points in sealed chambers. TMJ disc explanted tissues, cell suspensions, and 3D gel constructs with seeded cells will each be measured and compared for consumption rates differences at varied solute concentrations and pH levels. The ultimate goal of this project will be to characterize the nutrient transport and consumption properties of the TMJ disc in an effort to better understand TMJ disorders related to pathological loading and disc derangement. PUBLIC HEALTH RELEVANCE: This project will study biomechanical etiology of TMJ disc degeneration as well as determine benchmarks that can serve as predictors of TMJ disorders in clinical applications. Characterization of the nutrient transport and consumption rates is a preliminary step in defining the potential causes and symptoms of TMJ disorders. A better understanding of the cause of the disease is necessary to properly treat the problem rather than just the symptoms for the millions of Americans suffering from TMJ disorders.